U.S. patent number 8,784,248 [Application Number 13/638,401] was granted by the patent office on 2014-07-22 for engine start control device of hybrid vehicle.
This patent grant is currently assigned to Toyota Jidosha Kabushiki Kaisha. The grantee listed for this patent is Akira Murakami, Hiroyuki Ogawa, Takahiro Shiina, Daisuke Tomomatsu. Invention is credited to Akira Murakami, Hiroyuki Ogawa, Takahiro Shiina, Daisuke Tomomatsu.
United States Patent |
8,784,248 |
Murakami , et al. |
July 22, 2014 |
Engine start control device of hybrid vehicle
Abstract
In an engine start control device of a hybrid vehicle including
a power dividing mechanism which has a sun roller, a carrier, and a
first disc with which a rotating shaft of a first motor/generator,
an output shaft of an engine, and an output shaft of a second
motor/generator are coupled, respectively and by which differential
rotating operations between the sun roller, the carrier, and the
first disc are controlled using an alignment chart on which
rotation speeds of the sun roller, the carrier, and the first disc
are disposed in the sequence of the sun roller, the carrier, the
first disc and shown by straight lines.
Inventors: |
Murakami; Akira (Gotenba,
JP), Ogawa; Hiroyuki (Susono, JP), Shiina;
Takahiro (Susono, JP), Tomomatsu; Daisuke
(Susono, JP) |
Applicant: |
Name |
City |
State |
Country |
Type |
Murakami; Akira
Ogawa; Hiroyuki
Shiina; Takahiro
Tomomatsu; Daisuke |
Gotenba
Susono
Susono
Susono |
N/A
N/A
N/A
N/A |
JP
JP
JP
JP |
|
|
Assignee: |
Toyota Jidosha Kabushiki Kaisha
(Toyota-shi, JP)
|
Family
ID: |
44711533 |
Appl.
No.: |
13/638,401 |
Filed: |
March 30, 2010 |
PCT
Filed: |
March 30, 2010 |
PCT No.: |
PCT/JP2010/055757 |
371(c)(1),(2),(4) Date: |
September 28, 2012 |
PCT
Pub. No.: |
WO2011/121743 |
PCT
Pub. Date: |
October 06, 2011 |
Prior Publication Data
|
|
|
|
Document
Identifier |
Publication Date |
|
US 20130019712 A1 |
Jan 24, 2013 |
|
Current U.S.
Class: |
475/5; 475/196;
475/3; 475/4; 180/65.235; 475/189 |
Current CPC
Class: |
B60W
20/40 (20130101); B60K 6/445 (20130101); B60K
6/543 (20130101); B60K 6/365 (20130101); B60W
10/06 (20130101); Y10T 74/137 (20150115); F16H
2037/0873 (20130101); F16H 37/086 (20130101); F16H
15/52 (20130101); Y02T 10/6239 (20130101); F16H
15/50 (20130101); Y02T 10/62 (20130101) |
Current International
Class: |
F16H
3/72 (20060101); F16H 13/08 (20060101); F16H
37/06 (20060101); F16H 15/48 (20060101); B60K
6/445 (20071001) |
Field of
Search: |
;475/3,4,5,189,196
;180/65.235 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
|
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|
|
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|
9 170533 |
|
Jun 1997 |
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JP |
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2003 278856 |
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Oct 2003 |
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JP |
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2005-138803 |
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Jun 2005 |
|
JP |
|
2005 278281 |
|
Oct 2005 |
|
JP |
|
2006-199077 |
|
Aug 2006 |
|
JP |
|
2006 519349 |
|
Aug 2006 |
|
JP |
|
2007-084065 |
|
Apr 2007 |
|
JP |
|
2008 222173 |
|
Sep 2008 |
|
JP |
|
2009 40132 |
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Feb 2009 |
|
JP |
|
2009 190693 |
|
Aug 2009 |
|
JP |
|
2009-227195 |
|
Oct 2009 |
|
JP |
|
2009 255683 |
|
Nov 2009 |
|
JP |
|
2010-000935 |
|
Jan 2010 |
|
JP |
|
Other References
International Search Report Issued Jun. 1, 2010 in PCT/JP10/055757
Filed Mar. 30, 2010. cited by applicant .
International Search Report issued Jun. 1, 2010, in
PCT/JP2010/055756, filed Mar. 30, 2010 (with English language
translation). cited by applicant .
Office Action mailed Feb. 27, 2014, in co-pending U.S. Appl. No.
13/638,728. cited by applicant.
|
Primary Examiner: Lewis; Tisha
Attorney, Agent or Firm: Oblon, Spivak, McClelland, Maier
& Neustadt, L.L.P.
Claims
The invention claimed is:
1. An engine start control device of a hybrid vehicle, comprising:
a differential mechanism that includes first to third rotating
elements with which a rotating shaft of a first electric rotating
machine, an output shaft of an engine, and a rotating shaft of a
second electric rotating machine are coupled, respectively, a
fourth rotating element having a center axis of rotation common to
the first to third rotating elements, and rolling members which
have a center axis of rotation different from the center axis of
rotation as well as can transmit power via contact portions between
the first rotating element, the third rotating element, and the
fourth rotating element and are held by the second rotating element
and by which differential rotating operations between the first to
third rotating elements are controlled using an alignment chart on
which rotation speeds of the first to third rotating elements are
disposed in the sequence of the first rotating element, the second
rotating element, and the third rotating element and shown by
straight lines and in which a rotation speed axis of the second
rotating element internally divides between a rotation speed axis
of the first rotating element and a rotation speed axis of the
third rotating element by a relation of 1:.rho., wherein the
differential mechanism changes an internally divided ratio of
1:.rho. by changing a planetary gear ratio .rho. which is obtained
by dividing an absolute value of a relative rotation speed of the
third rotating element to the second rotating element on the
alignment chart by an absolute value of a relative rotation speed
of the first rotating element to the second rotating element by
changing a tilt angle of the rolling members, and when the engine
is cranked at the time the engine starts by transmitting a rotation
of the first electric rotating machine to the output shaft of the
engine, the planetary gear ratio .rho. is controlled on the
alignment chart so that a rotation speed of the first rotating
element is increased.
2. The engine start control device of the hybrid vehicle according
to claim 1, wherein when a rotating speed of the first rotating
element is increased at the time the rolling members are disposed
in contact between a radially outside portion of the first rotating
element and radially inside portions of the third rotating element
and the fourth rotating element, respectively, the planetary gear
ratio .rho. is made smaller than a predetermined value on the
alignment chart.
3. The engine start control device of the hybrid vehicle according
to claim 1, wherein when the rolling members are disposed in
contact between a radially outside portion of the third rotating
element and radially inside portions of the first rotating element
and the fourth rotating element, respectively, the alignment chart
assumes that a rotation speed axis of the second rotating element
internally divides between a rotation speed axis of the third
rotating element and a rotation speed axis of the first rotating
element in a relation of 1:.rho.a by a planetary gear ratio .rho.a
which is obtained by dividing an absolute value of a relative
rotation speed of the first rotating element to the second rotating
element by an absolute value of a relative rotation speed of the
third rotating element to the second rotating element, and when a
rotation speed of the first rotating element is increased, the
planetary gear ratio .rho.a is made larger than a predetermined
value on the alignment chart.
4. An engine start control device of a hybrid vehicle, comprising:
a differential mechanism that includes first to fourth rotating
elements with which a rotating shaft of a first electric rotating
machine, an output shaft of an engine, an output shaft toward a
drive wheel side, and a rotating shaft of a second electric
rotating machine are coupled, respectively and rolling members
which have a center axis of rotation different from a common center
axis of rotation in the first to fourth rotating elements, can
transmit power via contact portions between the first rotating
element, the third rotating element, and the fourth rotating
element, and held by the second rotating element and by which
differential rotating operations between the first to fourth
rotating elements are controlled using an alignment chart on which
rotation speeds of the first to fourth rotating elements are
disposed in the sequence of the first rotating element, the second
rotating element, the third rotating element, and the fourth
rotating element and shown by straight lines and in which a
rotation speed axis of the second rotating element internally
divides between a rotation speed axis of the first rotating element
and a rotation speed axis of the third rotating element by a
relation of 1:.rho.1 and a rotation speed axis of the second
rotating element internally divides between the rotation speed axis
of the first rotating element and a rotation speed axis of the
fourth rotating element by a relation of 1:.rho.2, wherein the
differential mechanism changes internally divided ratios of
1:.rho.1 and 1:.rho.2 by changing a first planetary gear ratio
.rho.1 which is obtained by dividing an absolute value of a
relative rotation speed of the third rotating element to the second
rotating element by an absolute value of a relative rotation of the
first rotating element to the second rotating element and a second
planetary gear ratio .rho.2 which is obtained by dividing an
absolute value of a relative rotation speed of the fourth rotating
element to the second rotating element by an absolute value of a
relative rotation of the first rotating element to the second
rotating element on the alignment chart by changing a tilt angle of
the rolling members, and when the engine is cranked at the time the
engine starts by transmitting a rotation of the first electric
rotating machine to the output shaft of the engine, the first and
second planetary gear ratios .rho.1, .rho.2 are controlled on the
alignment chart so that a rotation speed of the first rotating
element is increased.
5. The engine start control device of the hybrid vehicle according
to claim 4, wherein when a rotation speed of the first rotating
element is increased at the time the rolling members are disposed
in contact with a radially outside portion of the first rotating
element and radially inside portions of the third rotating element
and the fourth rotating element, the first planetary gear ratio
.rho.1 is made smaller than a predetermined value and the second
planetary gear ratio .rho.2 is made larger than a predetermined
value on the alignment chart.
6. The engine start control device of the hybrid vehicle according
to claim 4, wherein when the rolling members are disposed in
contact between a radially outside portion of the third rotating
element and radially inside portions of the first rotating element
and the fourth rotating element, respectively, the alignment chart
disposes rotation speeds of the first to fourth rotating elements
in the sequence of the third rotating element, the second rotating
element, the first rotating element, and the fourth rotating
element and shows the rotating elements by straight lines and
assumes that a rotation speed axis of the second rotating element
internally divides between a rotation speed axis of the third
rotating element and a rotation speed axis of the first rotating
element in a relation of 1:.rho.a1 by a first planetary gear ratio
.rho.a1 which is obtained by dividing an absolute value of a
relative rotation speed of the first rotating element to the second
rotating element by an absolute value of a relative rotation speed
of the third rotating element to the second rotating element and a
rotation speed axis of the second rotating element internally
divides between a rotation speed axis of the third rotating element
and a rotation speed axis of the fourth rotating element in a
relation 1:.rho.a2 by a second planetary gear ratio .rho.a2 which
is obtained by dividing an absolute value of a relative rotation
speed of the fourth rotating element to the second rotating element
by an absolute value of a relative rotation speed of the third
rotating element to the second rotating element, and when a
rotation speed of the first rotating element is increased, the
first planetary gear ratio .rho.a1 is made larger than a
predetermined value and the second planetary gear ratio .rho.a2 is
made smaller than a predetermined value.
7. The engine start control device of the hybrid vehicle according
to claim 1, wherein the differential mechanism includes a sun
roller as the first rotating element, a carrier as the second
rotating element, a first disc as the third rotating element, a
second disc as the fourth rotating element, and planetary balls as
the rolling members.
8. The engine start control device of the hybrid vehicle according
to claim 1, wherein the differential mechanism includes a first
disc as the first rotating element, a carrier as the second
rotating element, a sun roller as the third rotating element, a
second disc as the fourth rotating element, and planetary balls as
the rolling members.
9. The engine start control device of the hybrid vehicle according
to claim 2, wherein when the cranking is executed, a rotation speed
of the second rotating element is set to at least a rotation speed
necessary for cranking as well as a rotation speed of the third
rotating element is reduced to 0 at the maximum on the alignment
chart.
10. The engine start control device of the hybrid vehicle according
to claim 1, wherein when the cranking is executed, the rotation
ratio is controlled when a temperature of a secondary battery as a
power supply source to the first electric rotating machine is a low
temperature or a high temperature than when an ordinary
temperature.
11. The engine start control device of the hybrid vehicle according
to claim 2, wherein the differential mechanism includes a sun
roller as the first rotating element, a carrier as the second
rotating element, a first disc as the third rotating element, a
second disc as the fourth rotating element, and planetary balls as
the rolling members.
12. The engine start control device of the hybrid vehicle according
to claim 4, wherein the differential mechanism includes a sun
roller as the first rotating element, a carrier as the second
rotating element, a first disc as the third rotating element, a
second disc as the fourth rotating element, and planetary balls as
the rolling members.
13. The engine start control device of the hybrid vehicle according
to claim 5, wherein the differential mechanism includes a sun
roller as the first rotating element, a carrier as the second
rotating element, a first disc as the third rotating element, a
second disc as the fourth rotating element, and planetary balls as
the rolling members.
14. The engine start control device of the hybrid vehicle according
to claim 3, wherein the differential mechanism includes a first
disc as the first rotating element, a carrier as the second
rotating element, a sun roller as the third rotating element, a
second disc as the fourth rotating element, and planetary balls as
the rolling members.
15. The engine start control device of the hybrid vehicle according
to claim 4, wherein the differential mechanism includes a first
disc as the first rotating element, a carrier as the second
rotating element, a sun roller as the third rotating element, a
second disc as the fourth rotating element, and planetary balls as
the rolling members.
16. The engine start control device of the hybrid vehicle according
to claim 6, wherein the differential mechanism includes a first
disc as the first rotating element, a carrier as the second
rotating element, a sun roller as the third rotating element, a
second disc as the fourth rotating element, and planetary balls as
the rolling members.
17. The engine start control device of the hybrid vehicle according
to claim 3, wherein when the cranking is executed, a rotation speed
of the second rotating element is set to at least a rotation speed
necessary for cranking as well as a rotation speed of the third
rotating element is reduced to 0 at the maximum on the alignment
chart.
18. The engine start control device of the hybrid vehicle according
to claim 5, wherein when the cranking is executed, a rotation speed
of the second rotating element is set to at least a rotation speed
necessary for cranking as well as a rotation speed of the third
rotating element is reduced to 0 at the maximum on the alignment
chart.
19. The engine start control device of the hybrid vehicle according
to claim 6, wherein when the cranking is executed, a rotation speed
of the second rotating element is set to at least a rotation speed
necessary for cranking as well as a rotation speed of the third
rotating element is reduced to 0 at the maximum on the alignment
chart.
20. The engine start control device of the hybrid vehicle according
to claim 2, wherein when the cranking is executed, the rotation
ratio is controlled when a temperature of a secondary battery as a
power supply source to the first electric rotating machine is a low
temperature or a high temperature than when an ordinary
temperature.
Description
FIELD
The present invention relates to an engine start control device of
a hybrid vehicle including at least an engine and an electric
rotating machine as a power source.
BACKGROUND
Conventionally, hybrid vehicles including an engine and an electric
rotating machine as a power source are known. Further, in this type
of hybrid vehicles, there are also known hybrid vehicles provided
with a power dividing mechanism capable of distributing input power
at a predetermined distribution ratio and outputting the
distributed input power.
For example, Patent Literature 1 shown below discloses a hybrid
vehicle provided with a differential mechanism (power dividing
mechanism) composed of a planetary gear mechanism including a
carrier with which an output shaft of an internal combustion engine
(engine) is coupled, a sun gear with which a rotating shaft of a
first motor/generator (electric rotating machine) is coupled, and a
ring gear with which a drive wheel side is coupled. The hybrid
vehicle of the Patent Literature 1 is also provided with another
differential mechanism in addition to the power dividing mechanism,
and the another differential mechanism includes a pinion gear with
which the output shaft of the internal combustion engine is coupled
and a sun gear with which the rotating shaft of the first
motor/generator is coupled via a clutch and is used as a start
differential mechanism of the internal combustion engine. When the
internal combustion engine of the hybrid vehicle starts, a rotation
speed of the rotating shaft of the first motor/generator is reduced
by connecting the rotating shaft of the first motor/generator to
the start differential mechanism via a clutch and transmitted to
the output shaft of the internal combustion engine, and the
internal combustion engine is cranked.
Patent Literature 2 shown below discloses a drive system of a
hybrid vehicle provided with a distribution mechanism (power
dividing mechanism) composed of a planetary gear mechanism
including a carrier with which an output shaft of an engine is
coupled, a sun gear with which a rotating shaft of a first
motor/generator is coupled, and a ring gear with which a rotating
shaft of a second motor/generator is coupled as well as the
rotating shaft of the second motor/generator is also coupled with a
drive wheel side. In the hybrid vehicle of Patent Literature 2,
when the engine is started, rotation torque of the first
motor/generator is transmitted to the engine via the power dividing
mechanism in a state that a vehicle is stopped by a parking brake
and the like and the engine is cranked.
Patent Literature 3 shown below discloses a drive system of a
hybrid vehicle provided with a power dividing mechanism for
distributing power of an engine to a first motor/generator and to a
drive wheel side at a predetermined distribution ratio. The drive
system employs a planetary cone mechanism capable of changing the
distribution rate as the power dividing mechanism. Further, Patent
Literature 4 shown below discloses a continuously variable
transmission provided with a continuously variable mechanism, which
includes balls (rolling members) clamped by an input disc and an
output disc and changes a transmission ratio by adjusting a tilt
angle of the balls, and a planetary gear mechanism (differential
mechanism) with which one of rotating elements is coupled with an
output shaft of the continuously variable mechanism. Specifically,
Patent Literature 4 describes the planetary gear mechanism
configured such that a sun gear as one of the rotating elements is
coupled with the output shaft of the continuously variable
mechanism, a carrier is coupled with a drive wheel side, and a ring
gear is coupled with an output side of a drive force source via a
gear group.
CITATION LIST
Patent Literature
Patent Literature 1: Japanese Patent Application Laid-open No.
2009-190693 Patent Literature 2: Japanese Patent Application
Laid-open No. H09-170533 Patent Literature 3: Japanese Patent
Application Laid-open No. 2009-040132 Patent Literature 4: Japanese
National Publication of International Patent Application No.
2006-519349
SUMMARY
Technical Problem
However, the hybrid vehicle of the Patent Literature 1 is
disadvantageous in that since the dedicated start differential
mechanism and clutch are necessary to start the engine, a size of a
drive system is increased at least by the size of the start
differential mechanism and the clutch. In the hybrid vehicle of
Patent Literature 2, since the first motor/generator capable of
generating a large amount of output torque for the cranking
operation is necessary to start the engine, there is a high
possibility that the first motor/generator having a large physical
constitution is mounted and a drive device is increased in
size.
Accordingly, an object of the present invention is to provide an
engine start control device of a hybrid vehicle capable of
improving the disadvantages of the conventional examples and
suppressing an increase in size of a drive system for starting an
engine.
Solution to Problem
In order to achieve the above mentioned object, an engine start
control device of a hybrid vehicle according to the present
invention includes a differential mechanism that includes first to
third rotating elements with which a rotating shaft of a first
electric rotating machine, an output shaft of an engine, and a
rotating shaft of a second electric rotating machine are coupled,
respectively and by which differential rotating operations between
the first to third rotating elements are controlled using an
alignment chart on which rotation speeds of the first to third
rotating elements are disposed in the sequence of the first
rotating element, the second rotating element, and the third
rotating element and shown by straight lines, wherein the
differential mechanism can change a rotation ratio obtained by
dividing a rotation speed of the first rotating element by a
rotation speed of the third rotating element, and when a rotation
of the first electric rotating machine is transmitted to the output
shaft of the engine and the engine is cranked at the time the
engine starts, a rotation ratio between the first rotating element
and the third rotating element is controlled on the alignment chart
so that the rotation speed of the first rotating element is
increased.
Here, it is desirable that the differential mechanism includes a
fourth rotating element having a center axis of rotation common to
the first to third rotating elements and rolling members which have
a center axis of rotation different from the center axis of
rotation as well as can transmit power via contact portions between
the first rotating element, the third rotating element, and the
fourth rotating element and are held by the second rotating
element, and the differential mechanism desirably changes the
rotation ratio according to a tilt angle of the rolling
members.
Further, it is desirable that the differential mechanism is
configured such that the first to third rotating elements has a
common center axis of rotation as well as the differential
mechanism includes rolling members which are disposed in contact
between a radially outside portion of the first rotating element
and a radially inside portion of the third rotating element,
respectively, held by the second rotating element, and have a
center axis of rotation different from the center axis of rotation.
In this case, when the rotation ratio is controlled, the rotation
ratio is desirably made smaller than a predetermined value on the
alignment chart.
The differential mechanism desirably includes a fourth rotating
element which has a center axis of rotation common to the first to
third rotating elements and is disposed in a state that a radially
inside portion is caused to be in contact with the rolling members,
can transmit power via contact portions between the first rotating
element, the third rotating element, and the fourth rotating
element, and the rolling members, and can change the rotation ratio
according to a tilt angle of the rolling members.
Further, The differential mechanism is desirably configured such
that the first to third rotating elements have a common center axis
of rotation as well as the differential mechanism desirably
includes rolling members which are disposed in contact between a
radially inside portion of the first rotating element and a
radially outside portion of the third rotating element,
respectively, held by the second rotating element, and a have
center axis of rotation different from the center axis of rotation.
In this case, when the rotation ratio is controlled, the rotation
ratio is desirably made larger than a predetermined value on the
alignment chart.
The differential mechanism desirably includes a fourth rotating
element which has a center axis of rotation common to the first to
third rotating elements and is disposed in a state that a radially
inside portion is caused to be in contact with the rolling members,
can transmit power via contact portions between the first rotating
element, the third rotating element, and the fourth rotating
element, and the rolling members, and can change the rotation ratio
according to a tilt angle of the rolling members.
Further, in order to achieve the above mentioned object, an engine
start control device of a hybrid vehicle according to the present
invention includes a differential mechanism that includes first to
fourth rotating elements with which a rotating shaft of a first
electric rotating machine, an output shaft of an engine, an output
shaft toward a drive wheel side, and a rotating shaft of a second
electric rotating machine are coupled, respectively and by which
differential rotating operations between the first to fourth
rotating elements are controlled using an alignment chart on which
rotation speeds of the first to fourth rotating elements are
disposed in the sequence of the first rotating element, the second
rotating element, the third rotating element, and the fourth
rotating element and shown by straight lines, wherein the
differential mechanism can change a rotation ratio obtained by
dividing a rotation speed of the first rotating element by a
rotation speed of the third rotating element and a rotation ratio
obtained by dividing the rotation speed of the first rotating
element by a rotation speed of the fourth rotating element, and
when a rotation of the first electric rotating machine is
transmitted to the output shaft of the engine and the engine is
cranked at the time the engine starts, a rotation ratio between the
first rotating element and the third rotating element and a
rotation ratio between the first rotating element and the fourth
rotating element are controlled on the alignment chart so that the
rotation speed of the first rotating element is increased.
Here, it is desirable that the differential mechanism has a center
axis of rotation different from a center axis of rotation in the
first to fourth rotating elements and includes rolling members
which can transmit power via contact portions between the first
rotating element, the third rotating element, and the fourth
rotating element and held by the second rotating element, and the
differential mechanism desirably changes the rotation ratio
according to a tilt angle of the rolling members.
Further, it is desirable that the differential mechanism is
configured such that the first to fourth rotating elements have a
common center axis of rotation as well as the differential
mechanism includes rolling members which are disposed in contact
between a radially outside portion of the first rotating element
and a radially inside portion of the third rotating element,
respectively, held by the second rotating element, and have a
center axis of rotation different from the center axis of rotation.
In this case, when the rotation ratio is controlled, a rotation
ratio between the first rotating element and the third rotating
element is desirably made smaller than a predetermined value as
well as a rotation ratio between the first rotating element and the
fourth rotating element is made larger than a predetermined value
the on the alignment chart.
The differential mechanism can desirably transmit power via contact
portions between the first rotating element, the third rotating
element, and the fourth rotating element, and the rolling members,
dispose the fourth rotating element in a state that a radially
inside portion is in contact with the rolling members as well as
change the rotation ratio according to a tilt angle of the rolling
members.
Further, it is desirable that the differential mechanism is
configured such that the first to fourth rotating elements have a
common center axis of rotation as well as the differential
mechanism includes rolling members which are disposed in contact
between a radially inside portion of the first rotating element and
a radially outside portion of the third rotating element,
respectively, held by the second rotating element, and have a
center axis of rotation different from the center axis of rotation.
In this case, when the rotation ratio is controlled, a rotation
ratio between the first rotating element and the third rotating
element is desirably made larger than a predetermined value as well
as a rotation ratio between the first rotating element the fourth
rotating element is desirably made smaller than a predetermined
value the on the alignment chart.
The differential mechanism can desirably transmit power via contact
portions between the first rotating element, the third rotating
element, and the fourth rotating element, and the rolling members,
dispose the fourth rotating element in a state that a radially
inside portion is in contact with the rolling members as well as
change the rotation ratio according to a tilt angle of the rolling
members.
Further, it is possible that the differential mechanism includes a
sun roller as the first rotating element, a carrier as the second
rotating element, a first disc as the third rotating element, a
second disc as the fourth rotating element, and planetary balls as
the rolling members.
Further, it is possible that the differential mechanism includes a
first disc as the first rotating element, a carrier as the second
rotating element, a sun roller as the third rotating element, a
second disc as the fourth rotating element, and planetary balls as
the rolling members.
It is desirable that when the cranking is executed, a rotation
speed of the second rotating element is set to at least a rotation
speed necessary for cranking as well as a rotation speed of the
third rotating element is reduced to 0 at the maximum on the
alignment chart.
Further, it is desirable that when the cranking is executed, the
rotation ratio is controlled when a temperature of a secondary
battery as a power supply source to the first electric rotating
machine is a low temperature or a high temperature than when an
ordinary temperature.
Advantageous Effects of Invention
Since the engine start control device of the hybrid vehicle
according to the present invention can increase the rotation speed
of the first rotating element, torque generated by the first
electric rotating machine for cranking can be reduced. Accordingly,
since the first electric rotating machine can generate the torque
for the cranking even by the small amount of torque, a rotation
speed of the engine can be increased up to a rotation speed
necessary to start the engine. Accordingly, the first electric
rotating machine can be made compact by reducing its capacity,
which can make the drive system of the hybrid vehicle compact.
Further, since no special dedicated parts are necessary to start
the engine, the drive system can be made more compact.
BRIEF DESCRIPTION OF DRAWINGS
FIG. 1 is a view illustrating an engine start control device of a
hybrid vehicle according to the present invention and a drive
system of a first embodiment.
FIG. 2 is an alignment chart of the drive system of the first
embodiment.
FIG. 3 is a view illustrating a power flow of the drive system in a
state illustrated in FIG. 2.
FIG. 4 is an alignment chart of the drive system of the first
embodiment and is a view illustrating a state when a cranking
control of the first embodiment is executed.
FIG. 5 is a view illustrating a power flow of the drive system in a
state illustrated in FIG. 4.
FIG. 6 is a view illustrating another configuration of the drive
system of the first embodiment.
FIG. 7 is an alignment chart of a drive system of a second
embodiment and is a view illustrating a state when a secondary
battery is at an ordinary temperature.
FIG. 8 is an alignment chart of the drive system of the second
embodiment and is a view illustrating a state when the secondary
battery is at a low temperature or a high temperature.
FIG. 9 is a view illustrating an example of a map of a planetary
gear ratio according to a temperature of the secondary battery.
FIG. 10 is a view illustrating another example of the map of the
planetary gear ratio according to the temperature of the secondary
battery.
FIG. 11 is a view illustrating an engine start control device of a
hybrid vehicle according to the present invention and a drive
system of a third embodiment.
FIG. 12 is an alignment chart of the drive system of the third
embodiment and is a view illustrating a state when a cranking
control of the third embodiment is executed.
FIG. 13 is a view illustrating a power flow of the drive system in
a state illustrated in FIG. 12.
FIG. 14 is a view illustrating another mode of the drive
system.
FIG. 15 is a view illustrating other mode of the drive system.
DESCRIPTION OF EMBODIMENTS
Embodiments of an engine start control device of a hybrid vehicle
according to the present invention will be explained below in
detail based on drawings. Note that the present invention is not
limited by the embodiments.
First Embodiment
A first embodiment of the engine start control device of the hybrid
vehicle according to the present invention will be explained based
on FIGS. 1 to 6.
The engine start control device of the first embodiment is composed
of a control unit 1 (electronic control unit: ECU) illustrated in
FIG. 1. The control unit 1 may have only a control function of the
engine start control device or may have other control functions.
The first embodiment employs the latter case.
First, the hybrid vehicle to which the engine start control device
is applied, more specifically, a drive system of the hybrid vehicle
will be described in detail based on FIG. 1.
The drive system illustrated in FIG. 1 includes plural types of
power sources and a power transmission system for transmitting
power of the power sources to drive wheels (not illustrated) as
drive force. As the power sources, there are prepared a mechanical
power source which uses mechanical energy converted from heat
energy as power and an electric power source which uses mechanical
energy converted from electric energy as power.
The drive system includes an engine 10 for outputting mechanical
power (engine torque) from an output shaft (crank shaft) 11 as the
mechanical power source. An internal combustion engine and an
external combustion engine are considered as the engine 10. The
engine 10 permits operations such as fuel injection and ignition
performed by the control unit 1.
The drive system uses first and second electric rotating machines
20, 30, which are configured as any of a motor, a generator capable
performing a powering drive, or a motor/generator capable of
performing both a powering drive and a regeneration drive, as
electric a power source.
Here, explanation will be made by exemplifying the motor/generator.
Accordingly, hereinafter, the first and second electric rotating
machines 20, 30 are called first and second motor/generators 20, 30
(MG 1, MG 2) respectively. The first and second motor/generators
20, 30 are configured as, for example, a permanent magnet type
alternating current synchronous motor and can perform operations
such as a powering drive operation by the control unit 1 via a not
illustrated inverter. At the time of powering drive, the first and
second motor/generators 20, 30 convert electric energy supplied
from a secondary battery 51 to mechanical energy via the inverter
and outputs mechanical power (motor torque) from rotating shafts
21, 31 which are disposed coaxially with a not illustrated rotor.
In contrast, at the time of regeneration drive, when mechanical
power (motor torque) is input to the first and second
motor/generators 20, 30 from the rotating shafts 21, 31, the first
and second motor/generators 20, 30 convert the mechanical energy to
electric energy. The electric energy can be stored in the secondary
battery 51 as electric power via the inverter and can be used as
electric power when the other motor/generator performs the powering
drive.
The power transmission system is prepared with a power dividing
mechanism 40 which can distribute input power at a predetermined
distribution ratio and output the distributed power. The power
dividing mechanism 40 is configured as a differential mechanism
which permits differential rotating operations between rotating
elements. An explanation will be made exemplifying a so-called
traction planetary gear mechanism composed of rotating
elements.
The power dividing mechanism 40 includes a sun roller 41, plural
planetary balls 42, a carrier 43, and first and second discs 44, 45
as the rotating elements. Among the rotating elements, the sun
roller 41, the carrier 43, and the first and second discs 44, 45
have a common center axis of rotation X. In contrast, each
planetary ball 42 has a center axis of rotation different from the
center axis of rotation X and rotates (rotates on its center axis
of rotation) and rotates (revolves) around the center axis of
rotation X. Hereinafter, unless otherwise particularly described, a
direction along the center axis of rotation X is called an axis
direction and a direction about the center axis of rotation X is
called a circumferential direction. A direction orthogonal to the
center axis of rotation X is called a radial direction, and a side
of the radial direction facing inside is called an inside radial
direction and a side thereof facing outside is called an outside
radial direction.
The sun roller 41 is located at a center of rotation of the power
dividing mechanism 40 and is configured as, for example, a
cylindrical rotary member having the center axis of rotation X as
its center axis. An outer peripheral surface of the sun roller 41
acts as a rolling surface when the planetary balls 42 rotate on
their center axis of rotation. The sun roller 41 may cause the
planetary balls 42 to roll by a rotating operation thereof or may
be rotated by a rolling operation of the planetary balls 42.
The planetary balls 42 correspond to ball type pinions in the
traction planetary gear mechanism and are radially disposed at
approximately equal intervals to a radially outside portion (here,
outer peripheral surface) of the sun roller 41 about the center
axis of rotation X. Further, the planetary balls 42 are disposed
between the radially outside portion of the sun roller 41 and
radially inside portions (here, inner peripheral surfaces) of the
first and second discs 44, 45 in contact with each other. The
planetary balls 42 can transmit power between the sun roller 41 and
the first disc 44 and the second disc 45 via the contact portions
thereof. Since the planetary balls 42 are disposed as rolling
members which rotate on their center axes of rotation between the
sun roller 41 and the first and second discs 44, 45, although the
planetary balls 42 are preferably a perfect spherical member, they
may be formed to have an oval sectional shape as in, for example, a
rugby ball.
Each planetary ball 42 is rotatably supported by a support shaft
42a passing through a center thereof. For example, the planetary
ball 42 can relatively rotate (that is, can rotate on its center
axis of rotation) with respect to the support shaft 42a via a
bearing (not illustrated) interposed between the planetary ball 42
and an outer peripheral surface of the support shaft 42a.
Accordingly, the planetary balls 42 can roll on the outer
peripheral surface of the sun roller 41 about the support shafts
42a.
The support shafts 42a are disposed so that center axes thereof are
located on a plane including the center axis of rotation X. As
illustrated in FIG. 1, positions acting as references of the
support shafts 42a are positions at which the center axes of the
support shafts 42a are in parallel with, for example, the center
axis of rotation X. The support shaft 42a can be swung (tilted)
between the reference position and a position tilted from the
reference position. The support shaft 42a is tilted in a plane
including the center axis of the support shafts 42a and the center
axis of rotation X. The tilt operation is performed by a shift
mechanism attached to both ends of the support shaft 42a projecting
from an outside peripheral curved surface of the planetary ball
42.
The shift mechanism tilts the planetary ball 42 together with the
support shaft 42a by operating tilt arms 46 attached to both the
ends of the support shaft 42a.
The tilt arms 46 are members for applying tilt force to the support
shaft 42a and the planetary ball 42 and tilting a center axis of
rotation of the planetary ball 42, that is, a center axis of the
support shaft 42a. A pair of the tilt arms 46 is prepared to a
support shaft 42a and a planetary ball 42. For example, the tilt
arms 46 are molded and disposed so as to extend in a direction
vertical with respect to the center axis of rotation X. Radially
outside ends of the tilt arms 46 are attached to ends of the
support shafts 42a, respectively. One of the pair of the tilt arms
46 moves radially outward and the other of the tilt arms 46 moves
radially inward to thereby apply the tilt force to the support
shaft 42a and the planetary ball 42. The tilt arms 46 are operably
accommodated and held in grooves formed to disc portions 43a of the
carriers 43. The grooves are aligned with a number of the tilt arms
46 and formed radially about the center axis of rotation X.
Accordingly, the tilt arms 46, the support shafts 42a, and the
planetary balls 42 rotate together with the carriers 43.
Although not shown, the shift mechanism is further provided with
push members for moving the tilt arms 46 radially outward or
radially inward and drive units for operating the push members. The
tilt force is generated by moving the push members in the axis
direction and applying push force of the push members to radially
inside portions of the tilt arms 46. For example, the pair of the
tilt arms 46 which support the support shafts 42a has radially
inside extreme ends whose wall surfaces confronting with each other
in the axis direction are tapered radially inward. Further, wall
surfaces of both ends of the push members in the axis direction act
as contact surfaces in contact with the extreme end taper surfaces
of the tilt arms 46, and the contact surfaces are formed in a shape
tapering radially outward. With the configuration, when the push
force of the push members is applied to the tilt arms 46, since the
tilt arms 46 are pushed upward radially outward, the support shafts
42a are tilted and the planetary balls 42 are tilted in association
with the tilt operation of the support shafts 42a. As a tilt angle
of the planetary ball 42, a reference position of FIG. 1 is set to,
for example, 0 degree. The drive units are, for example, an
electrically driven actuator such as an electrically driven motor
or a hydraulic pressure actuator and are operated by being
controlled by the control unit 1.
The carrier 43 is a rotating member which can rotate relatively to
the sun roller 41 and the first and second discs 44, 45. The
carrier 43 has a pair of disc potions 43a which uses the center
axis of rotation X as a center axis. The disc potions 43a are
disposed at positions where the disc potions 43a sandwich the
planetary balls 42, the support shafts 42a and the tilt arms 46 in
the axis direction. The disc potions 43a are integrated by not
illustrated rod-like support portions. With the configuration, the
carrier 43 holds the planetary balls 42, the support shafts 42a and
the tilt arms 46 so as to prevent them from relatively moving in
the axis direction with respect to the sun roller 41. Further, as
the carrier 43 rotates, the carrier 43 rotates the planetary balls
42, the support shafts 42a and the tilt arms 46 about the center
axis of rotation X by the grooves of the disc potions 43a described
above.
The first and second discs 44, 45 are rotating members formed in an
annular shape or a disc shape using the center axis of rotation X
as a center axis, and are disposed to sandwich the planetary balls
42 in confrontation with each other in the axis direction.
Specifically, the first and second discs 44, 45 have contact
surfaces which come into contact with radially outside peripheral
curved surfaces of the planetary balls 42. The contact surfaces
have a concave arc surface having a curvature similar to that of
the outside peripheral curved surface of the planetary ball 42. The
contact surfaces are formed so that distances from the center axis
of rotation X to the contact portions with the planetary balls 42
have the same length and contact angles of the first and second
discs 44, 45 to the planetary balls 42 have the same angle. The
contact angle is an angle from the reference to the contact
portions in contact with the planetary balls 42. Here, a radial
direction is used as the reference. The contact surfaces are in
point contact or in line contact with the outer peripheral curved
surfaces of the planetary balls 42. Note that a contact line in the
line contact faces a direction orthogonal to a plane when the
planetary balls 42 described above tilt. The contact surfaces are
formed such that when axis-direction power toward the planetary
balls 42 is applied to the first and second discs 44, 45, power is
applied to the planetary balls 42 radially inward in an oblique
direction.
In the power dividing mechanism 40, when the planetary balls 42 has
the tilt angle of 0 degree, the first disc 44 and the second disc
45 rotate at the same number of rotations (at the same rotation
speed). That is, at the time, a rotation ratio (ratio of the number
of rotations) of the first disc 44 and the second disc 45 becomes
1. In contrast, when the planetary balls 42 are tilted from the
reference position, distances from the center axes of the support
shafts 42a to the contact portions in contact with the first disc
44 change as well as distances from the center axes of the support
shafts 42a to the contact portions in contact with the first disc
44 change. Accordingly, any one of the first disc 44 or the second
disc 45 rotates at a speed higher than when it is located at the
reference position and the other of the first disc 44 or the second
disc 45 rotates at a speed lower than when it is located at the
reference position. For example, when the planetary balls 42 are
tilted clockwise on a sheet of FIG. 1, the second disc 45 rotates
at a speed lower than the first disc 44 (a speed is increased),
whereas when the planetary balls 42 are tilted counterclockwise on
the sheet of FIG. 1, the second disc 45 rotates at a speed higher
than the first disc 44 (a speed is reduced). Accordingly, in the
power dividing mechanism 40, the rotation ratio between the first
disc 44 and the second disc 45 can be changed continuously by
changing the tilt angle of the planetary balls 42.
The power dividing mechanism 40 is provided with push units (not
illustrated) for pushing at least any one of the first or second
disc 44, 45 to the planetary balls 42 and generating nip-pressure
between the first and second discs 44, 45 and the planetary balls
42. The push units generate the nip-pressure between the first and
second discs 44, 45 and the planetary balls 42 by generating power
(push force) in the axis direction. The push force is set to a
magnitude by which torque can be transmitted between the sun roller
41 and the first and second discs 44, 45 via the planetary balls
42. For example, the push units may be a drive source such as an
electrically driven actuator and a hydraulic pressure actuator or
may be a mechanism such as a torque cam for generating the push
force as the first or second disc 44, 45 as a target for
disposition rotates. In the power dividing mechanism 40, the
nip-pressure is generated between the first and second discs 44, 45
and the planetary balls 42 by operating the push units so that the
push units generate the push force, and thereby friction force is
generated between the first and second discs 44, 45 and the
planetary balls 42.
In the power dividing mechanism 40, as the sun roller 41 rotates,
since the planetary balls 42 are rolled by the friction force,
rotation torque generated by that the planetary balls 42 rotate on
their axes is transmitted to the first and second discs 44, 45 and
rotate the first and second discs 44, 45. At the time, the carrier
43 rotates about the center axis of rotation X together with the
planetary balls 42, the support shafts 42a, and the tilt arms 46.
In the power dividing mechanism 40, the rotation torque, which is
generated by the planetary balls 42 which are caused to rotate on
their axes by the rotation of the first disc 44, is transmitted to
the sun roller 41 and the second disc 45 and rotates the sun roller
41 and the second disc 45. In the power dividing mechanism 40, the
rotation torque, which is generated by the planetary balls 42 which
are caused to rotate on their axes by the rotation of the second
disc 45 is transmitted to the sun roller 41 and the first disc 44
and rotates the sun roller 41 and the first disc 44. Further, in
the power dividing mechanism 40, since the planetary balls 42
rotate on their axes while revolving in association with the
rotation of the carrier 43, rotation torque generated by that the
planetary balls 42 rotate on their axes is transmitted to the sun
roller 41 and the first and second discs 44, 45 and rotates the sun
roller 41 and the first and second discs 44, 45.
In the first embodiment, the power dividing mechanism 40 is
connected to the power sources (engine 10 and first and second
motor/generators 20, 30) as described below.
First, the output shaft 11 of the engine 10 is coupled with the
carrier 43 (second rotating element). The output shaft 11 rotates
integrally with the carrier 43. Further, a rotating shaft 21 of the
first motor/generator 20 is coupled with the sun roller 41 (first
rotating element). The rotating shaft 21 rotates integrally with
the sun roller 41. Further, a rotating shaft 31 of the second
motor/generator 30 is coupled with the first disc 44 (third
rotating element). The rotating shaft 31 rotates integrally with
the first disc 44. In the drive system, the rotating shaft 31 of
the second motor/generator 30 acts also as an output shaft on the
system toward a drive wheel side.
The control unit 1 controls the drive system configured as
described above using alignment charts which show rotation speeds
(the number of rotations) of the first to third rotating elements
(the first disc 44 corresponds to the sun roller 41, the carrier
43, and a ring gear) by straight lines. An alignment chart
illustrated in FIG. 2 shows the rotation speeds of the sun roller
41, the carrier 43, and the first disc 44 by straight lines by
sequentially disposing coordinate axes in the order of the sun
roller 41, the carrier 43, and the first disc 44. In the alignment
charts, vertical axes, that is, the sun roller axis, the carrier
axis, and the first disc axis disposed sequentially from left show
the rotation speeds of the rotating elements. Portions of the
vertical axes above a horizontal axis show a positive rotation and
portions of the vertical axes below the horizontal axis shows a
negative rotation. Further, the horizontal axis shows a relation of
ratios (rotation ratios) of the rotation speeds of the sun roller
41, the carrier 43, and the first disc 44. In the alignment charts,
the carrier axis is determined at a position where the carrier axis
internally divides the sun roller axis and the first disc axis in a
relation of 1:.rho.. The .rho. is a value (rotation ratio) obtained
by dividing an absolute value of a relative rotation speed of the
first disc 44 to the carrier 43 by an absolute value of a relative
rotation speed of the sun roller 41 to the carrier 43, and is
so-called a planetary gear ratio.
The control unit 1 performs a start control of the engine 10 making
use of the alignment charts. In the drive system, when the engine
10 is started, a rotation of the first motor/generator 20 (MG 1) is
transmitted to the output shaft 11 and the engine 10 is cranked. At
the time, on the alignment charts, the rotation speed (number of
rotations) of the carrier 43 is set at least higher than a rotation
speed necessary for cranking (number of rotations necessary for
cranking) as well as a rotation speed of the first disc 44 is
reduced. As a result, since the rotation speed of the sun roller 41
increases on the alignment charts, torque of the first
motor/generator 20 necessary for cranking can be reduced. When, for
example, FIG. 2 is exemplified as an example, a state of a broken
line is shifted to a state of a solid line by reducing the rotation
speed of the first disc 44 than that at the time while keeping the
rotation speed necessary for cranking (here, the rotating speed is
reduced until the first disc 44 stops), and thereby the rotation
speed of the sun roller 41 is increased. With the operation, since
a rotation speed of the first motor/generator 20 is increased as
compared with the state of the broken line and the rotation speed
of the engine 10 can be increased up to the rotation speed
necessary for cranking by a small amount of motor torque, the
torque necessary for cranking the first motor/generator 20 can be
reduced. The rotation speed necessary for cranking is a rotation
speed necessary to start the engine 10 at which the fuel injection
and the like can be performed.
The cranking in a state that the planetary gear ratio .rho. is
fixed is similar to a cranking operation mode performed by a power
dividing mechanism composed of a conventional planetary gear
mechanism by which a planetary gear ratio .rho. cannot be changed.
In the state that the planetary gear ratio .rho. is fixed, since an
upper limit of the rotation speed of the sun roller 41 is
restricted by the rotation speed necessary for cranking in the
carrier 43 and by the rotation speed (0 at the lowest rotation
speed) of the first disc 44, an upper limit of the rotation speed
of the sun roller 41 is low and thus a still larger amount of
torque necessary for cranking must be generated by the first
motor/generator 20 to increase the rotation speed of the carrier 43
to the rotation speed necessary for cranking. Although a power flow
in the drive system at the time is illustrated in FIG. 3, to
increase motor torque (motor powering torque) of the first
motor/generator 20 to the torque necessary for cranking, a lot of
electric power must be supplied from the secondary battery 51 to
the first motor/generator 20.
Note that, at the time, to stop the first disc 44, a stop control
by supplying electric power from the secondary battery 51 and
stopping a rotation of the rotating shaft 31 of the second
motor/generator 30 is performed. In the stop control, electric
power having a magnitude according to the rotation speed of the sun
roller 41 is supplied to the second motor/generator 30 and the
second motor/generator 30 is caused to generate motor torque
capable of stopping the rotating shaft 31 (resistance torque having
a magnitude for canceling torque applied to the first disc 44 as
the sun roller 41 rotates). Since a higher rotation speed of the
sun roller 41 requires a larger amount of resistance torque, an
amount of the electric power to be supplied increases as the
rotation speed of the sun roller 41 becomes higher. To explain the
resistance torque in a different manner, the resistance torque
receives reaction force from a vehicle (drive wheel) side.
Since a large amount of the torque necessary for cranking requires
a capacity with correspondence with amount of the torque, which
increases the first motor/generator 20 in size and weight. In
general, an increase of a capacity of the motor/generator brings an
increase of a cost thereof. Further, to supply a large amount of
electric power, an electric circuit which withstands the large
amount of electric power is necessary, from which a cost is also
increased.
To cope with the problem, in the first embodiment, when the start
control of the engine 10 is performed, the planetary gear ratio
.rho. is controlled so that the rotation speed of the sun roller 41
coupled with the first motor/generator 20 is increased on an
alignment chart. When, for example, the start control of the engine
10 is performed, the planetary gear ratio .rho. is made smaller
than a predetermined value on an alignment chart illustrated in
FIG. 4 to thereby increase the rotation speed of the sun roller 41.
On the alignment chart at the time, the rotation speed of the
carrier 43 is set to a speed at which at least the rotation speed
necessary for cranking is kept as well as the rotation speed of the
first disc 44 is reduced than the rotation speed of the carrier 43.
Accordingly, the rotation speed of the sun roller 41 is increased
than when the planetary gear ratio .rho. is fixed (broken line) by
controlling the planetary gear ratio .rho.. When a request value
requested by the planetary gear ratio .rho. is determined, the
control unit 1 controls the tilt angle of the planetary balls 42 so
that the request value is satisfied. Note that, the rotation speed
of the first disc 44 is reduced up to 0 at which the rotation speed
is maximized (that is, the first disc 44 stops).
Accordingly, as illustrated in a power flow of FIG. 5, since the
torque necessary for cranking which must be generated by the first
motor/generator 20 can be reduced, the engine 10 can increase a
rotation speed of the output shaft 11 up to the rotation speed
necessary for cranking by a small amount of motor torque of the
first motor/generator 20. Accordingly, the first motor/generator 20
can reduce the size and the weight by reducing its capacity and
further can also reduce the cost. The reduction in size of the
first motor/generator 20 also leads to a reduction in size of drive
system. Further, since the amount of electric power supplied to the
first motor/generator 20 can be suppressed low, the cost of the
electric circuit can be reduced and an electric power consumption
of the secondary battery 51 can be suppressed. As a result, in the
first embodiment, since it can be avoided that the capacity of the
first motor/generator 20 becomes insufficient and the amount of the
electric power to be supplied becomes insufficient and thus the
engine 10 can be certainly cranked, a starting property of the
engine 10 can be improved. Further, in the first embodiment, since
no dedicated parts are necessary to start the engine, the engine
can be started at a low cost as well as the drive system can be
made more compact. Furthermore, in the first embodiment, the
traction planetary gear mechanism as described above is used to the
power dividing mechanism 40 capable of changing the planetary gear
ratio .rho., which contributes to a reduction in size and cost.
The predetermined value described above may be determined based on
a physical constitution (capacity) and a request value of cost of
the first motor/generator 20 to be mounted and a request value of
cost of the electric circuit. When, for example, it is desired to
reduce the capacity of the first motor/generator 20, the rotation
speed of the sun roller 41 is set to a rotation speed at which
torque necessary for cranking, which has a magnitude provided with
an upper limit corresponding to the desired capacity or with an
allowance can be generated, is determined on an alignment chart,
and a planetary gear ratio, which is shown by a straight line
connecting the rotation speed to the rotation speed necessary for
cranking in the carrier 43, is set to a predetermined value.
Incidentally, the first embodiment can be applied not only to the
drive system composed of the configuration described above but also
to a drive system having a mode of FIG. 6 shown below. The drive
system illustrated in FIG. 6 is configured such that a second
motor/generator 30 is disposed to the drive system illustrated in
FIG. 1 so as to cover an outer peripheral side of an approximately
cylindrical power dividing mechanism 40. In other words, in the
drive system, the power dividing mechanism 40 is disposed inside of
a rotor of the second motor/generator 30 coaxially with a center
axis of rotation X of the rotor.
Also in the drive system, a rotating shaft 31 of the second
motor/generator 30 is coupled with a first disc 44 so as to rotate
integrally therewith. In contrast, in the drive system of FIG. 1,
although the rotating shaft 31 is used as the output shaft of the
drive system facing the drive wheel side, in the drive system, an
output shaft 60 thereof is provided independently of the rotating
shaft 31 and coupled with the first disc 44 so as to rotate
integrally therewith.
The drive system can also achieve an operation and a working effect
similar to those of the drive system of FIG. 1. In the drive
system, since the second motor/generator 30 is disposed so as to
cover the outer peripheral side of the power dividing mechanism 40,
the second motor/generator 30 having a low-rotation/high-torque
specification as compared with the first motor/generator 20 can be
configured compact, and thus the drive system can achieve a more
reduction in size, weight, and cost than the drive system of FIG.
1.
Further, as described above, in the drive systems of FIG. 1 and
FIG. 6, the reaction force from the vehicle (drive wheel) side due
to engine torque and the like is received by the stop control of
the second motor/generator 30. With the operation, drive force is
prevented from being generated by the drive wheels due to the
engine start control. However, since the stop control requires
electric power of the secondary battery 51, a configuration which
does not need to execute the stop control may be arranged by
causing a vehicle stop device as described below to receive the
reaction force. For example, a wheel braking device capable of
adjusting brake force by a control performed by the control unit 1
can be considered as the vehicle stop device. In the case, the
control unit 1 controls an actuator of the braking device and
causes a wheel to generate brake force only capable of receiving
the reaction force. Further, a so-called parking device for
preventing a forward/backward travel of a vehicle in park can be
used as the vehicle stop device. When, for example, a shift lever
is located at an operation position (shift position P) of the
parking device when the vehicle stops, the stop control of the
second motor/generator 30 is not necessary. Further, even if the
shift lever is not located at the operation position, the stop
control of the second motor/generator 30 becomes unnecessary by
causing the control unit 1 to operate the parking device. As
described above, since an electric power consumption of the
secondary battery 51 necessary to the stop control can be
suppressed by making the stop control of the second motor/generator
30 unnecessary, fuel consumption can be improved.
Further, in the power dividing mechanism 40 of the drive system
exemplified in the first embodiment, the sun roller 41 is applied
as the first rotating element with which the first motor/generator
20 is coupled, and the first disc 44 is applied as the third
rotating element with which the rotating shaft 31 of the second
motor/generator 30 (which is used also as the output shaft on the
system toward the drive wheel side) is coupled. Accordingly, in the
exemplification, the planetary gear ratio .rho. is made smaller
than the predetermined value on the alignment chart illustrated in
FIG. 4 to increase the rotation speed of the sun roller 41 (that
is, the first motor/generator 20) when the start control of the
engine 10 is performed. In contrast, the power dividing mechanism
may use the first disc 44 as the first rotating element as well as
may use the sun roller 41 as the third rotating element. In the
case, the planetary gear ratio .rho.a is made larger than the
predetermined value on the alignment chart to increase the rotation
speed of the first motor/generator 20 when the start control of the
engine 10 is performed. Here, the planetary gear ratio .rho.a is a
value (rotation ratio) obtained by dividing an absolute value of a
relative rotation speed of the first disc 44 to the carrier 43 by
an absolute value of a relative rotation speed of the sun roller 41
to the carrier 43. In the alignment chart of the case, ".rho." is
read otherwise to ".rho.a", "the MG 1" and "the MG 2, the output
shaft" are read otherwise in, for example, the alignment chart
illustrated in FIG. 4. In the alignment chart, the rotation speed
of the carrier 43 is set so that at least the rotation speed
necessary for cranking is kept as well as the rotation speed of the
sun roller 41 is reduced than the rotation speed of the carrier 43.
Accordingly, the rotation speed of the first disc 44 is increased
as the planetary gear ratio .rho. is controlled. Note that the
rotation speed of the sun roller 41 is reduced until the sun roller
41 stops at the maximum.
Second Embodiment
A second embodiment of the engine start control device of the
hybrid vehicle according to the present invention will be explained
based on FIGS. 7 to 10.
The engine start control device of the second embodiment is
provided with a cranking operation control function described below
together with/or independently of a cranking operation control
function similar to that of the engine start control device of the
first embodiment described above. A control target of the engine
start control device of the second embodiment is the drive system
of FIG. 1 or FIG. 6 exemplified in the first embodiment. The
cranking operation control function in the second embodiment will
be described below in detail.
A performance of a secondary battery 51 may be sufficiently
exhibited or may be deteriorated depending on a usage environment
in which the secondary battery 51 is used. That is, although the
secondary battery 51 causes no problem when it is used in an
ordinary temperature region, when the secondary battery 51 is used
in a low temperature region and a high temperature region, its
performance may be deteriorated. The temperature region is
different depending on respective secondary batteries 51 and is
determined as a specification when the batteries 51 are designed.
Since the deterioration of performance of the secondary battery 51
results in a drop of an output of the secondary battery 51 and an
amount of electric power to be supplied to a first motor/generator
20 becomes insufficient, it becomes difficult to increase a
rotation speed of a carrier 43 (an output shaft 11 of an engine 10)
to a rotation speed necessary for cranking, and thus a starting
property of the engine 10 may be lowered. In contrast, at the time
of ordinary temperature at which the performance of the secondary
battery 51 can be exhibited without problem, although a necessary
and sufficient amount of electric power to be supplied can be
obtained, when a rotation speed of the first motor/generator 20
excessively increases, silence may be impaired at the time the
engine starts.
To cope with the problem, in the second embodiment, a control unit
1 is configured such that a planetary gear ratio .rho. is increased
more when the secondary battery 51 is at the ordinary temperature
than when the secondary battery 51 is at the low temperature and
the high temperature (FIG. 7), whereas the planetary gear ratio
.rho. is reduced more when the secondary battery 51 is at the low
temperature and the high the temperature than when the secondary
battery 51 is at the ordinary temperature (FIG. 8). The planetary
gear ratio .rho. is preferably set using a map shown below.
For example, as shown in a map of FIG. 9, when a temperature t of
the secondary battery 51 is in the ordinary temperature region, the
planetary gear ratio .rho. is set to become a predetermined value
.rho.a, when the temperature t of the secondary battery 51 is in
the low temperature region, the planetary gear ratio .rho. is set
to become a predetermined value .rho.b, and when the temperature t
of the secondary battery 51 is in the high temperature region, the
planetary gear ratio .rho. is set to become a predetermined value
.rho.c
(.rho.max.gtoreq..rho.a>.rho.c>.rho.b.gtoreq..rho.min). The
term ".rho.max" is a maximum value of the planetary gear ratio
which can be changed, and ".rho.min" is a minimum value of the
planetary gear ratio which can be changed. Values of the
predetermined values .rho.a, .rho.b, .rho.c are preferably
determined by an experiment and a simulation.
The predetermined value .rho.a is set to any value of the planetary
gear ratios .rho. by which the silence at the time the engine 10
starts can be kept within a request value in the ordinary
temperature region in which the performance of the secondary
battery 51 can be sufficiently exhibited. As a result, since the
rotation speed of the sun roller 41 can be reduced in the ordinary
temperature region, an engine rotation number can be gently
increased at the time of cranking, and thereby the silence can be
improved at the time the engine starts. Further, the predetermined
value .rho.a may be set to a minimum value or to a value near to
the minimum value in the planetary gear ratios .rho. by which the
silence can be kept within the request value in the ordinary
temperature region at the time, for example, the engine 10 starts.
When the predetermined value .rho.a is set as described above,
since the rotation speed of the sun roller 41 is not excessively
increased in the ordinary temperature region, the silence is
improved at the time the engine starts. Further, since the rotation
speed of the sun roller 41 at the time of cranking is set to a high
speed side within a range in which the silence can be kept, the
first motor/generator 20 can be reduced in size and weight as far
as possible, by which the drive system can be made compact and a
cost of an electric circuit can be reduced.
In the low temperature region or in the high temperature region in
which a deterioration of performance of the secondary battery 51 is
admitted, the predetermined value .rho.b or .rho.c is set to any
value of the planetary gear ratios .rho. at which the rotation
speed of the sun roller 41 (the first motor/generator 20) can be
increased in a degree by which insufficient motor torque (motor
powering torque) of the first motor/generator 20 due to a drop of
output of the secondary battery 51 can be compensated. As a result,
in the low temperature region and in the high temperature region, a
rotation speed of the carrier 43 (the output shaft 11 of the engine
10) can be increased up to the rotation speed necessary for
cranking even by a small amount of motor torque of the first
motor/generator 20, and thereby the engine 10 can be started. Note
that the predetermined value .rho.b is smaller than the
predetermined value .rho.c. This is because the performance of the
secondary battery 51 is more likely to be deteriorated in the low
temperature region than in the high temperature region.
As described above, according to the map of the FIG. 9, the silence
at the time the engine starts is improved in the ordinary
temperature region as well as the starting property of the engine
10 is in the low temperature region and the high temperature region
improved.
When strictly examined, the performance of the secondary battery 51
is deteriorated even in the ordinary temperature region as the
ordinary temperature region approaches the low temperature region
and the high temperature region. Likewise, the performance of the
secondary battery 51 in the low temperature region and the high
temperature is improved as the low temperature region and the high
temperature are nearer to the ordinary temperature region.
Accordingly, the planetary gear ratio .rho. may be set by a map as
shown in FIG. 10. Here, a temperature at which a best performance
is exhibited is called the ordinary temperature. Further, for the
convenience of explanation, the predetermined values pa, .rho.b,
.rho.c (.rho.max.gtoreq..rho.a>.rho.c>.rho.b.gtoreq..rho.min)
of FIG. 9 are used.
In the map of FIG. 10, the planetary gear ratio .rho. is set to the
predetermined value .rho.a at the time of ordinary temperature.
Further, in the map, during a time in which the temperature t of
the secondary battery 51 reaches from the ordinary temperature to a
certain temperature of the low temperature region, the planetary
gear ratio .rho. is gradually reduced from the predetermined value
.rho.a to the predetermined value .rho.b as the temperature t
decreases. Even if the certain temperature is in, for example, the
low temperature region, the certain temperature is set to a
temperature at which the starting property of the engine 10 can be
secured without reducing the planetary gear ratio .rho. to the
predetermined value .rho.b. If a temperature at which the starting
property can be secured does not exist in the low temperature
region, it may be set, for example, a boundary temperature between
the low temperature region and the ordinary temperature region as
the certain temperature. Further, in the map, during a time in
which the temperature t of the secondary battery 51 reaches from
the ordinary temperature to a certain temperature of the high
temperature region, the planetary gear ratio .rho. is gradually
reduced from the predetermined value .rho.a to the predetermined
value .rho.c as the temperature t increases. Even if the certain
temperature is in, for example, the high temperature region, the
certain temperature is set to a temperature at which the starting
property of the engine 10 can be secured without reducing the
planetary gear ratio .rho. to the predetermined value .rho.b. If a
temperature at which the starting property can be secured does not
exist in the high temperature region, it may be set, for example, a
boundary temperature between the low temperature region and the
ordinary temperature region as the certain temperature.
The silence can be improved at the time the engine starts on the
ordinary temperature side and the starting property of the engine
10 on the low temperature side and the high temperature side can be
improved even using the map of FIG. 10.
Third Embodiment
A third embodiment of the engine start control device of the hybrid
vehicle according to the present invention will be explained based
on FIGS. 11 to 13.
The engine start control device of the third embodiment uses a
drive system illustrated in FIG. 11 as a control target. The drive
system is configured such that, in the drive system illustrated in
FIG. 6 of the first embodiment described above, the rotating shaft
31 of the second motor/generator 30 is coupled with the second disc
45 in place of the first disc 44. The rotating shaft 31 is rotated
integrally with the second disc 45. Accordingly, the drive system
of the third embodiment can achieve an effect of a reduction in
size likewise the drive system illustrated in FIG. 6.
The drive system is controlled by a control unit 1 using an
alignment chart of FIG. 12. The alignment chart disposes coordinate
axes in the order of a sun roller 41 (first rotating element), the
carrier 43 (second rotating element), the first disc 44 (third
rotating element), and the second disc 45 (fourth rotating element)
and shows rotation speeds thereof by a straight line. In the
alignment chart, vertical axes show rotation speeds of the rotating
elements and are a sun roller axis, a carrier axis, a first disc
axis, and a second disc axis sequentially from the left. Further,
horizontal axes show a relation of rotation speed ratios (rotation
ratios) of the sun roller 41, the carrier 43, the first disc 44,
and the second disc 45. In the alignment chart, the carrier axis is
determined at a position which internally divides between the sun
roller axis and the first disc axis in a relation of 1:.rho.1 as
well as between the sun roller axis and the second disc axis in a
relation of 1:.rho.2. The first planetary gear ratio .rho.1 is a
value (rotation ratio) obtained by dividing an absolute value of a
relative rotation speed of the first disc 44 to the carrier 43 by
an absolute value of a relative rotation speed of the sun roller 41
to the carrier 43. Further, the second planetary gear ratio .rho.2
is a value (rotation ratio) obtained by dividing an absolute value
of a relative rotation speed of the second disc 45 to the carrier
43 by an absolute value of a relative rotation speed of the sun
roller 41 to the carrier 43. A relation of the first planetary gear
ratio .rho.1 and the second planetary gear ratio .rho.2 is
determined by a tilt angle of the planetary balls 42.
In the drive system configured as described above, when a start of
the engine 10 is controlled, the first and second planetary gear
ratios .rho.1, .rho.2 are controlled so that a rotation speed of
the sun roller 41 coupled with the first motor/generator 20 is
increased on the alignment chart. When, for example, the start of
the engine 10 is controlled, the first planetary gear ratio .rho.1
is made smaller than a first predetermined value as well as the
second planetary gear ratio .rho.2 is made larger than a second
predetermined value on the alignment chart illustrated in FIG. 12
so that the rotation speed of the sun roller 41 is increased. In
the alignment chart at the time, a rotation speed of the carrier 43
is set so that at least a rotation speed necessary for cranking is
kept as well as a rotation speed of the first disc 44 is reduced
than the rotation speed of the carrier 43. Accordingly, the
rotation speed of the sun roller 41 is increased by controlling the
first and second planetary gear ratios .rho.1, .rho.2. When request
values of the first planetary gear ratio .rho.1 and the second
planetary gear ratio .rho.2 are determined, the control unit 1
controls the tilt angle of the planetary balls 42 so that the
request values are satisfied. Note that, here, the rotation speed
of the first disc 44 is reduced to 0 at which the rotation speed is
maximized (that is, until the first disc 44 stops).
The first planetary gear ratio .rho.1 and the second planetary gear
ratio .rho.2 are determined so as to fall within a width of a range
of a rotation ratio between the first disc 44 (D1) and the second
disc 45 (D2) on the alignment chart (that is, transmission range).
The range of the rotation ratio is determined by a specification of
the power dividing mechanism 40. Further, when one of the first
planetary gear ratio .rho.1 and the second planetary gear ratio
.rho.2 is determined, the other of them is inevitably determined.
Accordingly, when, for example, an emphasis is mainly placed on a
reduction of a capacity of the first motor/generator 20, the first
planetary gear ratio .rho.1 may be determined, and further when an
emphasis is mainly placed on an output amount of motor torque of
the second motor/generator 30, the second planetary gear ratio
.rho.2 may be determined. A first predetermined value when the
first planetary gear ratio .rho.1 is determined may be determined
likewise the predetermined value shown in the first embodiment. For
example, the rotation speed of the sun roller 41 may be set to a
rotation speed, at which a torque load necessary for cranking
having a magnitude provided with an upper limit corresponding to a
capacity of the first motor/generator 20 to be determined or an
allowance (strictly, it is preferable to take a torque load
necessary for cranking of the second motor/generator 30 into
consideration) can be generated, on an alignment chart and a
planetary gear ratio shown by a straight line which connects the
rotation speed to a rotation speed necessary for cranking in the
carrier 43 may be set to the first predetermined value. Further, as
to a second predetermined value when the second planetary gear
ratio .rho.2 is determined, it is preferable to determine the
rotation speed of the second disc 45 to a rotation speed which can
generate a torque load necessary for cranking having a magnitude
which can be output or is desired to be output under a horizontal
axis and to set a planetary gear ratio shown by a straight line
which connects the rotation speed to the rotation speed necessary
for cranking in the carrier 43 to the second predetermined
value.
In the second embodiment, as shown in a power flow of FIG. 13, the
first motor/generator 20 and the second motor/generator 30 partly
satisfy the torque necessary for cranking, respectively. That is,
in the second embodiment, at the time of engine start control,
cranking of the engine 10 can be controlled using the motor torque
of the second motor/generator 30 (torque load of the second
motor/generator 30 necessary for cranking). Further, the torque
load necessary for cranking which must be generated by the first
motor/generator 20 can not only be reduced by a reason similar to
the first embodiment but also more reduced because the motor torque
of the second motor/generator 30 can be also used. Accordingly, the
first motor/generator 20 can be more reduced in size, weight, and
cost than the first embodiment, by which the drive system can be
further reduced in size and weight, and a cost of an electric
circuit can be further reduced. Thus, in the second embodiment, the
starting property of the engine 10 can be further improved.
When the control unit 1 performs the cranking control, it is
preferable to cause the control unit 1 to control the drive system
so that a relation of the first and second motor/generators 20, 30
satisfy the following expression 1. In the expression 1, "Tmg1"
shows motor torque of the first motor/generator 20, and "Tmg2"
shows motor torque of the second motor/generator 30. Further, "Tes"
shows a magnitude of engine torque necessary to start the engine
10. Tmg1*(1+.rho.1)+Tmg2*(.rho.2-.rho.1)=Tes*.rho.1 (1)
In the second embodiment, reaction force from a vehicle (drive
wheel) side due to engine torque and the like is not applied to the
first disc 44 (first disc axis) coupled with an output shaft 60
toward a drive wheel side by satisfying the relation. That is, in
the second embodiment, since no torque is transmitted to drive
wheels at the time the engine starts, a generation of drive force
in the drive wheels can be suppressed. Accordingly, in the case, a
generation of shock by transmitting the torque can be suppressed as
well as a stop control of the vehicle by the vehicle stop device
and the like described above is not necessary at the time of engine
start control.
In the power dividing mechanism 40 of the drive system exemplified
in the second embodiment, the sun roller 41 is applied as the first
rotating element with which the first motor/generator 20 is
coupled, and the first disc 44 is applied as the third rotating
element with which the output shaft 60 on the system toward the
drive wheel side is coupled. Accordingly, in the exemplification,
to increase the rotation speed of the sun roller 41 (that is, the
first motor/generator 20) at the time of start control of the
engine 10, the first planetary gear ratio .rho.1 is made smaller
than the first predetermined value as well as the second planetary
gear ratio .rho.2 is made larger than the second predetermined
value on the alignment chart illustrated in FIG. 12. In contrast,
the power dividing mechanism may use the first disc 44 as the first
rotating element as well as may use the sun roller 41 as the third
rotating element. In the case, to increase the rotation speed of
the first motor/generator 20 at the time of start control of the
engine 10, the first planetary gear ratio .rho.a1 is made larger
than the first predetermined value as well as the second planetary
gear ratio .rho.a2 is made smaller than the second predetermined
value on the alignment chart. Here, the first planetary gear ratio
.rho.a1 is a value (rotation ratio) obtained by dividing an
absolute value of a relative rotation speed of the first disc 44 to
the carrier 43 by an absolute value of a relative rotation speed of
the sun roller 41 to the carrier 43. Further, the second planetary
gear ratio .rho.a2 is a value (rotation ratio) obtained by dividing
an absolute value of a relative rotation speed of the second disc
45 to the carrier 43 by an absolute value of a relative rotation
speed of the sun roller 41 to the carrier 43. The alignment chart
in the case, ".rho.1" and ".rho.2" are read otherwise to ".rho.a1"
and ".rho.a2", respectively, "MG 1" and "output shaft" are read
otherwise in, for example, the alignment chart illustrated in FIG.
12, respectively. In the alignment chart, the rotation speed of the
carrier 43 is set so that at least the rotation speed necessary for
cranking is kept as well as the rotation speed of the sun roller 41
is reduced than the rotation speed of the carrier 43. Accordingly,
the rotation speed of the first disc 44 is increases by controlling
the first and second planetary gear ratios .rho.a1, .rho.a2. Note
that the rotation speed of the sun roller 41 is reduced until it
stops at a maximum.
Incidentally, although the output shaft 11 of the engine 10 in the
first and second embodiments described above is exemplified
assuming that the output shaft 11 is connected to the carrier 43 on
the outer peripheral surface side of the sun roller 41 (strictly,
on an outer peripheral surface of a support shaft for rotatably
supporting the sun roller), in the drive system illustrated in FIG.
1, 6, or 11, the support shaft may be composed of a hollow shaft
and the output shaft 11 may be connected to the carrier 43 through
a hollow portion. The drive system modified as described above can
also achieve an effect similar to that of the drive system which is
illustrated in FIG. 1, 6 or 11 and acts as a base of the
modification. FIG. 14 shows an example of the modification. A drive
system of FIG. 14 improves the drive system illustrated in FIG. 11.
In the drive system of FIG. 14, the output shaft 11 is further
disposed on the first motor/generator 20 side and connected to the
carrier 43 via a center of an annular rotor in the first
motor/generator 20. With the configuration, in the drive system,
since an input and an output are disposed along a straight line on
both sides of the power dividing mechanism 40 located at a center
between the input and the output, respective elements can be simply
connected, and the drive system is particularly useful as a system
for a FR (front engine/rear drive) vehicle. Accordingly, the drive
system not only obtains an effect similar to that of the drive
system of FIG. 11 but also allows a reduction in size, weight, and
cost as a system for the FR vehicle.
Further, although the first motor/generator 20 of the drive system
described above and illustrated in FIG. 1, 6, 11 or 14 is disposed
in confrontation with the second disc on the center axis of
rotation X, the first motor/generator 20 may be disposed so as to
cover the outer peripheral side of the power dividing mechanism 40
in the drive system likewise the second motor/generator 30
illustrated in FIG. 6 and the like. The drive system modified as
described above can also achieve an effect similar to that that of
the drive system which is illustrated in FIG. 1, 6, 11 or 14 and
acts as a base of the modification. Further, since the drive system
can configure the second motor/generator 30 compact, an axis length
can be shortened, which allows a further reduction in size, weight,
and cost. FIG. 15 shows an example of the drive system. The drive
system of FIG. 15 improves the drive system illustrated in FIG. 11.
In the drive system of FIG. 15, since the second motor/generator 30
is configured also compact, an axis length is further shortened,
which allows a reduction in size, weight, and cost.
INDUSTRIAL APPLICABILITY
As described above, the engine start control device of the hybrid
vehicle according to the present invention is useful as a
technology for suppressing an increase of size of a drive system
for starting an engine.
REFERENCE SIGNS LIST
1 CONTROL UNIT 10 ENGINE 11 OUTPUT SHAFT 20 FIRST MOTOR/GENERATOR
(FIRST ELECTRIC ROTATING MACHINE) 21 ROTATING SHAFT 30 SECOND
MOTOR/GENERATOR (SECOND ELECTRIC ROTATING MACHINE) 31 ROTATING
SHAFT 40 POWER DIVIDING MECHANISM 41 SUN ROLLER 42 PLANETARY BALL
42a SUPPORT SHAFT 43 CARRIER 44 FIRST DISC 45 SECOND DISC 46 TILT
ARM 51 SECONDARY BATTERY 60 OUTPUT SHAFT X CENTER AXIS OF
ROTATION
* * * * *